[docs] Document project structure

[fyliu]

Overview

We need to create an explanation page for the project directory structure so that new devs can understand where everything is and should go.

Action Items

• Add a new page, something like project_structure.md and lay out and explain the project structure

Resources/Instructions

• docs/ for documentation
• app/ for the django application and also where the docker container's project root is
• scripts/ to store helper scripts callable from outside docker
• etc.

All the project files (some project-specific content omitted)

tree -L 4 -I __pycache__ -I venv -I __init__.py

├── app                                                                                                                                                                                                                                        
│   ├── core                                                                                                                                                                                                                                   
│   │   ├── admin.py                                                                                                                                                                                                                           
│   │   ├── api                                                                                                                                                                                                                       
│   │   │   ├── permissions.py                                                                                                                                                                                                                 
│   │   │   ├── serializers.py                                                                                                                                                                                                                 
│   │   │   ├── urls.py                                                                                                                                                                                                                        
│   │   │   └── views.py
│   │   ├── apps.py
│   │   ├── initial_data/
│   │   ├── migrations
│   │   │   ├── 0001_initial.py
│   │   │   ├── ...
│   │   │   └── max_migration.txt
│   │   ├── models.py
│   │   ├── scripts/
│   │   ├── tests
│   │   │   ├── conftest.py
│   │   │   ├── test_api.py
│   │   │   ├── test_models.py
│   │   │   └── test_permissions.py
│   │   └── utils
│   │       └── jwt.py
│   ├── data
│   │   └── migrations
│   │       ├── ...
│   │       └── max_migration.txt
│   ├── Dockerfile
│   ├── entrypoint.sh
│   ├── erd.png
│   ├── manage.py
│   ├── peopledepot
│   │   ├── asgi.py
│   │   ├── settings.py
│   │   ├── urls.py
│   │   └── wsgi.py
│   ├── requirements.in
│   ├── requirements.txt
│   ├── scripts
│   │   └── convert.py
│   ├── setup.cfg
│   └── tmp.md
├── CONTRIBUTING.md
├── docker-compose.yml
├── docs/
├── LICENSE
├── mkdocs.yml
├── pyproject.toml
├── README.md
└── scripts
    ├── buildrun.sh
    ├── check-migrations.sh
    ├── createsuperuser.sh
    ├── db.sh
    ├── erd.sh
    ├── lint.sh
    ├── loadenv.sh
    ├── logs.sh
    ├── migrate.sh
    ├── precommit-check.sh
    ├── run.sh
    ├── start-local.sh
    ├── test.sh
    └── update-dependencies.sh

• scripts, docs, initial data should be documented in their own pages